/*
 Copyright (c) 1997, 1998 Carnegie Mellon University.  All Rights
 Reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 1. Redistributions of source code must retain the above copyright notice,
 this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation
 and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
 derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 The AODV code developed by the CMU/MONARCH group was optimized and tuned by Samir Das and Mahesh Marina, University of Cincinnati. The work was partially done in Sun Microsystems.
 */

#include <assert.h>

#include <cmu-trace.h>

#include "aodvetx_rqueue.h"

#define CURRENT_TIME    Scheduler::instance().clock()
#define QDEBUG

/*
 Packet Queue used by AODVETX.
 */
aodvetx_rqueue::aodvetx_rqueue() {
    head_ = tail_ = 0;
    len_ = 0;
    limit_ = AODVETX_RTQ_MAX_LEN;
    timeout_ = AODVETX_RTQ_TIMEOUT;
}

void aodvetx_rqueue::enque(Packet *p) {
    struct hdr_cmn *ch = HDR_CMN(p);

    /*
     * Purge any packets that have timed out.
     */
    purge();
    p->next_ = 0;
    ch->ts_ = CURRENT_TIME + timeout_;
    if (len_ == limit_) {
        Packet *p0 = remove_head(); // decrements len_

        assert(p0);
        if (HDR_CMN(p0)->ts_ > CURRENT_TIME) {
            drop(p0, DROP_RTR_QFULL);
        } else {
            drop(p0, DROP_RTR_QTIMEOUT);
        }
    }

    if (head_ == 0) {
        head_ = tail_ = p;
    } else {
        tail_->next_ = p;
        tail_ = p;
    }
    len_++;
#ifdef QDEBUG
    verifyQueue();
#endif // QDEBUG
}

Packet*
aodvetx_rqueue::deque() {
    Packet *p;

    /*
     * Purge any packets that have timed out.
     */
    purge();
    p = remove_head();
#ifdef QDEBUG
    verifyQueue();
#endif // QDEBUG
    return p;
}

Packet*
aodvetx_rqueue::deque(nsaddr_t dst) {
    Packet *p, *prev;

    /*
     * Purge any packets that have timed out.
     */
    purge();
    findPacketWithDst(dst, p, prev);
    assert(p == 0 || (p == head_ && prev == 0) || (prev->next_ == p));

    if (p == 0)
        return 0;

    if (p == head_) {
        p = remove_head();
    } else if (p == tail_) {
        prev->next_ = 0;
        tail_ = prev;
        len_--;
    } else {
        prev->next_ = p->next_;
        len_--;
    }
#ifdef QDEBUG
    verifyQueue();
#endif // QDEBUG
    return p;

}

char aodvetx_rqueue::find(nsaddr_t dst) {
    Packet *p, *prev;

    findPacketWithDst(dst, p, prev);
    if (0 == p)
        return 0;
    else
        return 1;

}

/*
 Private Routines
 */

Packet* aodvetx_rqueue::remove_head() {
    Packet *p = head_;

    if (head_ == tail_) {
        head_ = tail_ = 0;
    } else {
        head_ = head_->next_;
    }
    if (p)
        len_--;

    return p;
}

void aodvetx_rqueue::findPacketWithDst(nsaddr_t dst, Packet*& p, Packet*& prev) {
    p = prev = 0;
    for (p = head_; p; p = p->next_) {
        //		if(HDR_IP(p)->dst() == dst) {
        if (HDR_IP(p)->daddr() == dst) {
            return;
        }
        prev = p;
    }
}

void aodvetx_rqueue::verifyQueue() {
    Packet *p, *prev = 0;
    int cnt = 0;

    for (p = head_; p; p = p->next_) {
        cnt++;
        prev = p;
    }
    assert(cnt == len_);
    assert(prev == tail_);
}

/*
 void
 aodvetx_rqueue::purge() {
 Packet *p;

 while((p = head_) && HDR_CMN(p)->ts_ < CURRENT_TIME) {
 // assert(p == remove_head());
 p = remove_head();
 drop(p, DROP_RTR_QTIMEOUT);
 }

 }
 */

bool aodvetx_rqueue::findAgedPacket(Packet*& p, Packet*& prev) {
    p = prev = 0;
    for (p = head_; p; p = p->next_) {
        if (HDR_CMN(p)->ts_ < CURRENT_TIME) {
            return true;
        }
        prev = p;
    }

    return false;
}

void aodvetx_rqueue::purge() {
    Packet *p, *prev;

    while (findAgedPacket(p, prev)) {
        assert(p == 0 || (p == head_ && prev == 0) || (prev->next_ == p));

        if (p == 0)
            return;

        if (p == head_) {
            p = remove_head();
        } else if (p == tail_) {
            prev->next_ = 0;
            tail_ = prev;
            len_--;
        } else {
            prev->next_ = p->next_;
            len_--;
        }
#ifdef QDEBUG
        verifyQueue();
#endif // QDEBUG
        p = prev = 0;
    }

}

